In his later years, George Habash, who has died of a heart attack, at an age believed to be 82, was often known as "the conscience of the Palestine revolution". He had been one of the very earliest founding fathers of that movement, which pioneered armed struggle and revolutionary violence as the sole means of liberating Palestine. Since it first emerged, in the 1960s as a potent new force on the Middle East stage, the movement suffered all manner of vicissitudes, and its ambitions were eventually reduced, almost out of recognition, to an endless series of surrenders to the exigencies of Pax Americana.

But, out of sincerity, rather than the opportunism which has tainted other, lesser radicals of his kind, "Al Hakim"(the doctor or wise man), remained faithful to his original conviction that by force - and force alone - could the Palestinians recover their rights. In 1967 he had been the founder, of the Popular Front for the Liberation of Palestine (PFLP). and he was to be faithful to his conviction that the rights he was fighting for included the recovery of the whole of original, pre-1948 Palestine, not just the additional territories which the Israelis conquered in 1967.

Born in Lydda, coastal Palestine, now part of Israel's second city Tel Aviv, to a family of Greek Orthodox grain merchants, Habash became a supreme example of that disposition, always latent in the Christian minority in those days, to display a greater militancy than the Moslem majority. There was already an idealistic strain in his choice of careers: like many others, he was a doctor before he was a politician. It was his personal experience of the 1948 disaster which, more than anything else, fired in him a determination to devote himself to the politics of struggle.

In 1948, as a 22-year-old undergraduate in medicine at the American University of Beirut he rushed back to Lydda to serve as a medical orderly as the Zionists advanced on the town and drove out its inhabitants. Within three years he and fellow-students from various parts of the Arab world founded the Arab Nationalist Movement, which believed that the Arabs should find the strength-through-unity to throw off western domination: that, in turn, would be the key to the liberation of Palestine. He graduated from university in 1951, first in class.

In the first of many a different place of exile, he settled in Amman, where he opened a "people's clinic" and a school for refugees. Accused of involvement in an attempt to overthrow King Hussein, and driven underground with a 33-year prison sentence on his head, he then fled to Syria, where, by a very natural transition, he became an ardent supporter of Egypt's President Gamal Nasser, the great pan-Arab hero of the times.

But if the price of sincerity can be a certain dogmatism, it was this which - so typically of his subsequent career - brought him into collision with mainstream sentiment in the still clandestine "revolution". Tiring of Arab inaction, Yasser Arafat and his Fatah guerrilla organisation had already embarked on their "popular liberation war".

Ironically, Habash at first opposed them, believing that Nasser should be permitted to make conventional war against Israel at a time of his own choosing. In a sense, the shattering defeat of the armies of Egypt. Jordan, Syria and Iraq in the six day war of 1967 proved him right.

But then, converted to armed struggle himself, he characteristically took it those extremes which have marked him, ever since, as one of the great patrons of "international terrorism" - though he was never to take on the demoniacal stature of the Venezuelan, Carlos the Jackal (Ilyich Ramirez Sanchez), or his fellow-Palestinian, Abu Nidal. For a brief, heady span, Habash and his newly formedPFLP held the world in thrall.

A series of hijackings included the events around Dawson's Field in September 1970. Two airliners, from Trans-World Airways and Swissair were hijacked to that former RAF base at Zerqa in the Jordanian desert, while an abortive takeover of an El Al airliner by the Nicaraguan Patrick Arguello, and the Palestinian Leila Khaled ended with Arguello dead and Khaled held at Ealing police station. A Pan Am jumbo jet was then hijacked to Cairo, via Beirut, and a British Overseas Airways Corporation VC10 to Dawson's Field to make the British free Khaled. This outrage helped precipitate Black September, King Hussein's assault on the guerrilla state-within-his-state, which ended with the King's victory, the first great strategic reverse in the fortunes of the Palestine "revolution". An exchange deal at the end of the month followed, freeing the remaining hostages, Khaled, and three other PFLP members.

Moving to Beirut, along with the rest of the PLO, Habash persisted in some of the more spectacular, publicity-seeking acts of violence - with the 1972 massacre of tourists at Lod (once Lydda and now Ben Gurion) airport by Japanese Red Army terrorists as perhaps the most successful, if ignoble, of them - but to less and less effect. The whole guerrilla movement was moving away from random terrorism of that kind, and, at the same time, looking more and more to diplomacy, first as a supplement to, then as substitute for, military action.

Habash, the radical, made it his business to resist every new stage of this growing moderation. But when, at the Palestine National Council (PNC) meeting in 1988, Arafat made his historic offer of a two-state solution to the Palestine problem, Habash did not walk out of the PLO altogether. Nor did he, three years later, when the PNC agreed to go to the 1991 Middle East peace conference in Madrid. He said he would respect the will of the majority, however fiercely he opposed it. That loyalty to Palestinian national unity, along with his personal modesty and simplicity, made him perhaps the most liked of the small, still surviving band of the revolution's original chiefs.

He stood down as PFLP leader in 2000, four years before the death of Yasser Arafat, and six years before the Islamicists of Hamas won their victory in the Palestinian election. Pax Americana meanwhile continues to make paltry progress in its regional diplomacy, and many of those who now so grudgingly support it may well in due course conclude that the "conscience of the revolution" had always been right in opposing it - and the whole concept of Palestinian moderation.

In 1961, he married his wife Hilda, and they had two daughters, Mesa, a doctor and Lama, an engineer.